An intraluminary prosthesis is a medical device used in the treatment of diseased bodily lumens. One type of intraluminary prosthesis used in the repair and/or treatment of diseases in various body vessels is a stent. A stent is generally a longitudinal tubular device formed of biocompatible material which is useful to open and support various lumens in the body. For example, stents may be used in the bodily vessel, such as in the coronary or peripheral vasculature, esophagus, trachea, bronchi colon, biliary tract, urinary tract, prostate, brain, as well as in a variety of other applications in the body. These devices are implanted within the vessel to open and/or reinforce collapsing or partially occluded sections of the lumen.
While stents are often made from metallic materials, the use of plastic stents is not uncommon, especially in non-vascular applications. For example, plastic stents have been used to treat malignant or benign strictures throughout the gastrointestinal tract because of, among other things, ease of placement and non-permanency of the stents. Benign strictures in biliary applications are often treated every three months with a plastic stent for up to about a year. Rigid plastic tubes were also used to treat esophageal strictures, but have been replaced by self-expanding stents.
Each year many patients are diagnosed with malignant biliary disease. Other diagnosis include benign disease, post surgical and questionable malignant. Typically, a patient with biliary disease presents symptoms such as jaundice, weight loss, abdominal pain, and back pain. These patients often suffer from an obstruction in the pancreaticobiliary ductal system. Numerous diseases can cause the inability of bile flow, however, the presence of gallstones and/or strictures is the most prevalent. For benign strictures, stenting or cathetering may be a useful resolution. Some stents or catheters, however, commonly get blocked and clog up. The patient often returns for another stent or catheter, where the physician often does not remove the previous stent or catheter and simply inserts another stent or catheter. Patients with benign strictures often have 4 to 5 stent or catheter packed into their common bile ducts. Usually, bile ducts can remodel, but 20% don't after multiple stent or catheter insertions.
Such plastic stents or catheters may have fairly thick walls. Such thick walls may make delivery through curved lumens difficult. Further, such thick walled devices may not be flexible.
Thus, there is a need for a polymeric stent which has improved patency by reducing re-intervention rates due, for example, to tumor in-growth, while still being flexible so that it can used in curved lumens.